Chemical Biological Radiological (CBR) Recovery – Modelling

The National Technical Advisory Group for chemical, biological or radiological (CBR) Recovery (NTAG-R) programme is a collaboration between DEFRA and Dstl to drive the development of tools, techniques, and capabilities to recover an incident site contaminated with CBR.

Background

The Department for Environment, Food and Rural Affairs asked Dstl to provide Operational Analysis support to understand, and plan for, the logistic requirements for Chemical Biological Radiological (CBR) Recovery.

A decision support capability was requested through use of a simulation model that can:

• Determine and quantify the items of CBR specific consumables, or equipment, that would be required in the Recovery Phase of a credible CBR incident.
• Determine strategies that can ensure access to these items (i.e. through stockpiling, call-off contracts or via strengthening supply chains).
• Provide initial assessment of these strategies through quantitative analysis.
• Inform decision-making by estimating the time taken to recover the incident site.
• Indicate which consumables are causing the most delays on the recovery activities.

Sagentia Defence were asked to define, develop, verify, and validate this simulation model, with a focus on strategic logistics planning, and produce the associated model documentation. The model was given the title ‘Environmental Recovery Involving CBR Agents’ (ERICA).

After initial development multiple spiral development cycles have occurred, delivering a bespoke product which captures the unique sequence of activities which need to happen in a CBR incident, as defined by DEFRA.

Approach

Model Operation –

ERICA simulates the recovery activities following a CBR release, where a contaminating agent is found across many items within a location. The user defines this location in terms of building blocks. For example: a street (site) comprises various houses (zones), which themselves are composed of many rooms (areas) each containing a number of objects. A defined set of activities are undertaken to recover the site (e.g. immediate disposal of a contaminating agent, processing of samples, scrubbing). The user selects which hazard reduction technology options are undertaken to clean the site, with a library of pre-populated options presented to the user for convenience and on-the-fly calculations to provide the user information about its effectiveness. The model performs a discrete-event simulation, allocating resources (e.g. teams of workers or specialised equipment) to undertake each activity required to achieve the site’s recovery, which includes scheduling of resources between each activity, tracking the consumption of consumables and resupplying these according to a user-defined lead-time, and calculating estimates of the time taken, waste generated and resource utilisation.

Model Structure –

The ERICA model comprises two high level components, a Data Management Tool and Site Planning Tool. The Data Management Tool is a Python front-end linking to an SQLite database, which allows the user to build a library of assets for use in generating CBR incidents to simulate.

The Site Planning Tool takes the assets built in the Data Management Tool and allows a user to:

• Build an incident site and define the contamination agent and level
• Plan the recovery by selecting the specific technology options to clean the site
• Run the discrete-event simulation of this recovery plan
• View the results of a simulation by viewing various histograms and numerical outputs

Outcome

ERICA supports the user’s site planning by providing information about the potential technology options and showing immediate impact of the likely time, waste and consumable requirements, as well as the effectiveness of the option, taking into consideration the surface area or volume of the object/area, the material from which the objects are made, and the contaminating agent present at the site. The SQLite and Python engine allows for total flexibility in the simulation, with the user having no practical limits to the number of zones, resources, consumables or time required to recover a site.